Support moment distribution during the back squat at different depths and loads in recreationally trained females

The squat is used in athletic and clinical settings. However, the coordination of the lower extremity during the lift is not well understood. The purpose was to compare the peak moments of the lower extremity joints at three squat depths (above parallel, parallel and full) and three squat loads (unloaded, 50 % 1 repetition maximum, and 85 % of depth specific 1 repetition maximum) and find their contribution to support (M_s).

Nineteen females performed squats in a randomized order.

Inverse dynamics and Winter's M_s equation were used to calculate peak moments of the hip, knee and ankle and calculate their contribution to M_s (α < 0.05).

Peak hip and ankle extensor moments varied with load but not depth and were greatest when using 85 % 1 repetition maximum. Peak knee extensor moments demonstrated a depth by load interaction. Within each depth as load increased so too did peak knee extensor moments and were highest squatting below parallel when loaded. The hip and knee contribution to M_s demonstrated a depth by load interaction while the ankle was only influenced by load. Within each depth as load increased hip contribution increased whereas the knee decreased contribution. When squatting with load the contribution of the hip decreased at below parallel while the knee increased.

To maximize peak hip moments squat with high load and to maximize peak knee moments squat deep with high load; however, depth and load dosages should be taken into consideration based on the status and goals of the individual.